1. Field of the Invention
The present invention relates to a thermal printer in which the ink of an ink ribbon is melted and printed on a recording sheet by the heat of a thermal head.
2. Description of the Prior Art
This known type of thermal printer has heretofore been equipped with a head raising and lowering mechanism which is arranged in such a manner as to, for printing, move a thermal head downwardly (a head-down state) so as to press it against a platen and, while not engaged in printing, move the thermal head upwardly (a head-up state) so as to separate it from the platen, a carriage moving mechanism which moves along the platen a carriage having a ribbon cassette which accommodates the thermal head and an ink ribbon, a sheet feed mechanism which feeds in accordance with a printing operation a recording sheet disposed on the front side of the platen. The head raising and lowering mechanism, the carriage moving mechanism, and the sheet feed mechanism are respectively actuated by different drive sources such as pulse motors.
As described above, the prior-art thermal printer needs at least three pulse motors in order to drive the head raising and lowering mechanism, the carriage moving mechanism and the sheet feed mechanism. This means that the manufacturing cost is disadvantageously high since a multiplicity of drive sources are needed and each of the motors is expensive.